MP24830HS-LF-Z全新原装原理图各脚功能电路原理芯片引脚定义-中国IC网-芯三七

MP24830

4.5V – 90V, Programmable Frequency

White LED Driver

The Future of Analog IC Technology

DESCRIPTION

FEATURES

The MP24830 is a 90V white LED driver

suitable for either step-down or inverting

step-up/down applications. It supports a wide

input range with excellent load and line

regulation. Its programmable current limit

provides customized applications with a wide

power range. Current mode operation provides

a fast transient response and eases loop

stabilization. Fault condition protection includes

thermal shutdown, cycle-by-cycle peak-current

limiting, open-string protection, and output

short-circuit protection.

•

Programmable Maximum Output Current

Unique Step-Up/Down Operation (Buck-

Boost Mode)

Wide 4.5V-to-90V Operating Input Range

for Step-Down Applications (Buck Mode)

Adjustable Switching Frequency

Analog and PWM Dimming

0.2V Reference Voltage

•

10μA Shutdown Mode

No Minimum LED Quantity Required

Stable with Low ESR Output Ceramic

Capacitors

The MP24830 incorporates both DC and PWM

dimming onto a single control pin. The separate

input reference ground pin allows for direct

enable and/or dimming control for a positive-to-

negative power conversion.

•

Cycle-by-Cycle Over-Current Protection

Thermal Shutdown Protection

Open-String Protection

Output Short-Circuit Protection

Available in 14-Pin SOIC and QFN

Packages

The MP24830 requires a minimal number of

readily-available external components. It is

available in 14-pin SOIC and QFN packages.

APPLICATIONS

•

General LED Illumination

Automotive LED Lighting

LCD Backlight

All MPS parts are lead-free, halogen free, and adhere to the RoHS directive. For

MPS green status, please visit MPS website under Quality Assurance.

“MPS” and “The Future of Analog IC Technology” are Registered Trademarks

of Monolithic Power Systems, Inc.

TYPICAL APPLICATION

13

3

VDD

BST

VIN

C1

C2

Rcs

Q1

MP24830

U1

2

CS

DR

SW

5

6

DIM

EN

DIM

EN

1

14

LED+

R9

499k

4

INGND

VSS

LED-

INGND

8

11

10

OVP

DIMO

FB

Q2

Si4100DY

12

RSET COMP

9

7

D2

C4

4.3nF

C3

100pF

C5

1nF

D1

R6

100k

C9

22pF

R7

R3

R10

4.7k

MP24830 Rev. 1.02

4/29/2015

www.MonolithicPower.com

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1

MP24830 — 4.5V–90V, PROGRAMABLE FREQUENCY WHITE LED DRIVER

ORDERING INFORMATION

Part Number

MP24830HS*

MP24830HL**

Package

SOIC-14

QFN-14

Top Marking

MP24830

24830

* For Tape & Reel, add suffix –Z (e.g. MP24830HS–Z);

For RoHS Compliant Packaging, add suffix –LF (e.g. MP24830HS–LF–Z)

** For Tape & Reel, add suffix –Z (e.g. MP24830HL–Z);

For RoHS Compliant Packaging, add suffix –LF (e.g. MP24830HL–LF–Z)

PACKAGE REFERENCE

TOP VIEW

14

13

12

1

2

3

4

5

6

7

DR

CS

SW

BST

VSS

14

13

12

11

DR

CS

1

2

3

4

5

6

7

SW

BST

VSS

DIMO

VDD

INGND

VDD

INGND

DIM

11 DIMO

FB

10

9

DIM

EN

10 FB

COMP

EN

9

8

COMP

OVP

8

RSET

OVP

RSET

EXPOSED PAD

ON BACKSIDE

SOIC14

QFN14

ABSOLUTE MAXIMUM RATINGS ⁽¹⁾

Supply Voltage V_DD– V_SS, V_CS– V_SS............90V

V_SW– V_SS..............................-0.3V to V_IN+ 0.3V

V_BST, V_DR..............................................V_SW+ 6V

V_EN– V_INGND, V_Dim– V_INGND............. -0.3V to +6V

Thermal Resistance ⁽⁴⁾θ_JAθ_JC

SOIC-14 .................................86 ......38 ...°C/W

QFN-14...................................49 ......10 ...°C/W

Notes:

1) Exceeding these ratings may damage the device.

2) The maximum allowable power dissipation is a function of the

maximum junction temperature T_J(MAX), the junction-to-

ambient thermal resistance θ_JA, and the ambient temperature

T_A. The maximum allowable continuous power dissipation at

any ambient temperature is calculated by P_D(MAX) = (T_J

(MAX)-T_A)/θ_JA. Exceeding the maximum allowable power

dissipation will cause excessive die temperature, and the

regulator will go into thermal shutdown. Internal thermal

shutdown circuitry protects the device from permanent

damage.

V_INGND– V_SS................................... -0.3V to 90V

Other pins – V_SS............................. -0.3V to +6V

(2)

Continuous Power Dissipation (T_A= +25°C)

SOIC-14 ....................................................1.4W

QFN-14......................................................2.6W

Junction Temperature..............................150°C

Lead Temperature ...................................260°C

Storage Temperature...............-65°C to +150°C

Recommended Operating Conditions ⁽³⁾

Supply Voltage V_DD– V_SS................ 4.5V to 85V

Operating Junction Temp. (T_J) -40°C to +125°C

3) The device function is not guaranteed outside of the

recommended operating conditions.

4) Measured on JESD51-7, 4-layer PCB.

MP24830 Rev. 1.02

4/29/2015

www.MonolithicPower.com

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2

MP24830 — 4.5V–90V, PROGRAMABLE FREQUENCY WHITE LED DRIVER

ELECTRICAL CHARACTERISTICES

V_IN= 12V, T_J= +25°C, all voltages with respect to V_SS, unless otherwise noted.

Parameters

Symbol Condition

Min Typ Max Units

0.192 0.2 0.208

Feedback Voltage

V_FB

I_FB

V_UVLOTH

V_UVLOHY

I_Q

V

nA

V

mV

mA

μA

Ω

V

A

4.5V ≤ V_IN≤ 90V

V_FB= 0.22V

Feedback Current

-50

3.7

50

4.4

Under Voltage Lockout Threshold Rising

Under Voltage Lockout Threshold Hysteresis

Operation Current (Quiescent)

Supply Current (Quiescent) at EN Off

Gate Driver Pull-Up Impedance

Gate Driver Pull-Down Impedance

Gate Driver Output-High to SW

Gate Driver Output-Low to SW

DIMO Source Current

4.1

160

0.8

10

V_EN= 2V, V_FB= 0.25V

V_EN=0V

1.1

23

I_OFF

R_{PULL UP}

R_{PULL Down}

V_OH-SW

V_OL-SW

I_DIMOSC

I_DIMOSK

V_DIMOH

V_DIMOL

25

7

I_DR=10mA

5.6

4.6

5.8

0.1

0.05

5

0.3

DIMO Sink Current

DIMO Output High

DIMO Output Low

A

V

I_DR=10mA

V_FB= 0.15V,

0.4

0.5

Oscillator Frequency

f_SW

145

30

215

265

kHz

R

_SET=100kΩ

V_FB= 0.15V,

_SET=380kΩ

Min. Oscillator Frequency

Max. Oscillator Frequency

f_SWMIN

f_SWMAX

50

75

kHz

R

V_FB= 0.15V, R_SETopen 245

365

465

V_FB= 0V, V_OVP=0V,

Foldback Frequency

f_SWFB

30

kHz

R

_SET=100kΩ

GM of Error Amplifier

GM

80

40

μs

Error Amplifier Output Current

I_Oamp

μA

Current Sensing Gain

G_CS

20

45

High-Side Current Limit Threshold

V_CLTH

mV

ns

V_FB= 0.19V,

_SET=100kΩ

Min. Off-Time

t_OFFMIN

280

R

Min. On-Time ⁽⁵⁾

EN Input Current

EN OFF Threshold (w/Respect to INGND)

EN ON Threshold (w/Respect to INGND)

Min. DIM Threshold

t_ON

I_ENIN

100

3.7

ns

μA

V

V_EN= 3.3V

V_ENOFFTHV_ENFalling

V_ENONTHV_ENRising

0.4

0.6

1.4

0.8

V_DIMTHL

V_DIMTHH

V_FB= 0.2V

0.7

Max. DIM Threshold

1.55 1.75 1.95

V

LED-Short Threshold for Immediate Latch-

Off

600

mV

LED Short Delay for Latch-Off

LED Short Threshold

450

300

160

1.2

50

μs

mV

°C

V

Thermal Shutdown ⁽⁵⁾

T_TSHD

V_OVPTH

V_OVPHY

Open LED OV Threshold

Open LED OV Hysteresis

1.1

1.3

mV

Notes:

5) Guaranteed by design.

MP24830 Rev. 1.02

www.MonolithicPower.com

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4/29/2015

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MP24830 — 4.5V–90V, PROGRAMABLE FREQUENCY WHITE LED DRIVER

PIN FUNCTIONS

SOIC14 Name Description

1

2

DR

CS

Driver Output. Connect it to the high-side MOSFET gate.

High-Side Current Sense. For over-current protection and current-mode control.

Supply Voltage. Operates from a 4.5V-to-85V unregulated input (with respect to VSS). Needs

C1 to prevent large input voltage spikes.

3

4

VDD

INGND Input Ground Reference. Reference for the EN/DIM signal.

Dimming Command Input. Selects for DC or PWM dimming. When the DIM pin voltage (with

respect to INGND) rises from 0.6V to 1.95V, the LED current changes from 0% to 100% of the

DIM maximum LED current. For PWM dimming, apply a 100Hz-to-2kHz square wave with an

amplitude greater than 2V. For combined analog and PWM dimming, apply a 100Hz-to-2kHz

square wave signal with amplitude from 0.6V to 1.95V.

5

6

7

EN

Enable.

Frequency Set. Connect a resistor to VSS to set the switching frequency, and a 1nF capacitor

to VSS to bypass the noise. Leaving this pin open for the 350kHz default operating frequency.

RSET

Over-Voltage Protection. Use a voltage divider to program OVP threshold. When the OVP pin

voltage reaches the 1.2V shutdown threshold, the switch turns off and recovers when the OVP

voltage decreases sufficiently. When the OVP pin voltage (with respect to VSS) falls below

0.4V and the FB pin voltage falls below 0.1V, the chip interprets this as a short circuit and the

operating frequency will fold back. Program the OVP pin voltage from 0.4V to 1.2V for normal

operation.

8

OVP

Error Amplifier Output. Connect a 1nF or larger capacitor on COMP and an RC network from

FB to COMP to improve the stability and to provide soft-start and PWM dimming.

9

COMP

FB

LED Current Feedback Input. A current-sensing resistor between FB and VSS provides circuit

feedback. The regulation voltage is 0.2V. Short-circuit protection triggers If the FB voltage

exceeds 300mV for 450µs or the FB voltage exceeds 600mV.

10

11

DIM Output. Provides for accurate PWM diming control following DIM logic. Connect to the

gate of the external dimming MOSFET. Leave floating if dimming accuracy is not a concern.

DIMO

Power Return. Connect to the circuit’s point of lowest potential, which is typically the anode of

the Schottky rectifier. Acts as the voltage reference for the regulated output voltage, and layout

requires extra consideration. Place this node outside of the D1-to-C1 ground path to prevent

switching current spikes from inducing voltage noise. Connect the exposed pad to this pin.

12

VSS

Bootstrap. Connect a capacitor between the SW and BST pins to form a floating supply across

13

14

BST the power switch driver. Use a 100nF or larger ceramic capacitor to provide sufficient energy

to drive the power switch’s gate above the supply voltage.

SW

Switch. Connect to the source of the external MOSFET

MP24830 Rev. 1.02

4/29/2015

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4

MP24830 — 4.5V–90V, PROGRAMABLE FREQUENCY WHITE LED DRIVER

TYPICAL PERFORMANCE CHARACTERISTICS

V_EN=5V, V_IN=5V to 85V, I_OUT=0.5A, L=47μH, T_A=25°C, unless otherwise noted.

Efficiency vs.

Input Voltage

Efficiency vs.

String Voltage

I

V

Line Regulation vs.

LED

IN

100

95

90

85

80

75

70

0.6

0.4

100

96

10LED

6LED

V_IN=40V

0.2

3LED

92

88

84

80

3LED

8LED

0.0

V_IN=20V

6LED

8LED

10LED

-0.2

-0.4

-0.6

0

20

40

60

80

100

10

15

20 25 30

35 40

10

20

30

40

50

60

70

V_INVOLTAGE (V)

LED STRING VOLTAGE (V)

INPUT VOLTAGE (V)

Buck Efficiency vs.

Input Voltage

Buck Efficiency vs.

String Voltage

Buck I

Line

LED

Regulation vs. V

IN

I

=1A

V

=50V, I

IN LED

=1A

2LED, I

=1A

LED

0.6

0.4

100

95

90

85

80

75

70

100

95

90

85

80

75

70

6LED

4LED

0.2

0.0

2LED

40

-0.2

-0.4

-0.6

0

20

60

80 100

5

12

19

26

33

40

20 30 40 50 60 70 80 90 100

V_INVOLTAGE (V)

LED STRING VOLTAGE (V)

INPUT VOLTAGE (V)

Buck-Boost I

vs.

Buck I

vs.

Buck-Boost I

vs.

LED

PWM Dimming

Analog Dimming

V

=25V, 3LED, F

=0.2kHz

V

=25V, 3LED, F

=0.2kHz

V

=20V, 3LED, F =0.2kHz

IN DIM

500

400

300

200

100

1000

800

600

400

200

0

500

400

300

200

100

0

20

40

60

80 100

0

20

40

60

80

100

0.7 0.9 1.1 1.3 1.5 1.7 1.9

DIMMING (%)

ANALOG DIMMING VOLTAGE (V)

MP24830 Rev. 1.02

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5

MP24830 — 4.5V–90V, PROGRAMABLE FREQUENCY WHITE LED DRIVER

TYPICAL PERFORMANCE CHARACTERISTICS (continued)

V_EN=5V, V_IN=5V to 85V, I_OUT=0.5A, L=47μH, T_A=25°C, unless otherwise noted.

V

CS

vs. Temperature

F

vs. Temperature

V

vs. Temperature

FB

SW

500

400

300

200

100

70

60

50

40

30

20

230

220

210

200

190

180

170

0

-50

-10

30

70 110 150

-50 -10

30

70 110 150

-50

-10

30

70 110 150

V

BST

vs. Temperature

I Current vs. Temperature

Q

140

7.0

1000

900

800

700

600

500

120

100

80

6.5

6.0

5.5

5.0

4.5

60

40

-50

-10

30

70 110 150

-50

-10

30

70 110 150

-50

-10

30

70 110 150

Buck ILED vs.

Buck-Boost Steady State

Buck Steady State

V

= 8V, 3LED, I

OUT

= 1A

V

= 14V, 1LED, I = 1A

OUT

IN

Analog Dimming

V

=20V, 3LED, I

=1A, F =0.2kHz

DIM

IN

OUT

1000

800

600

400

200

0

V

IN

50V/div.

20V/div.

V

SW

20V/div.

V

SW

20V/div.

V

OUT

5V/div.

V

OUT

10V/div.

I

L

1A/div.

0.7 0.9 1.1 1.3 1.5 1.7 1.9

ANALOG DIMMING VOLTAGE (V)

MP24830 Rev. 1.02

4/29/2015

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6

MP24830 — 4.5V–90V, PROGRAMABLE FREQUENCY WHITE LED DRIVER

TYPICAL PERFORMANCE CHARACTERISTICS (continued)

V_EN=5V, V_IN=5V to 85V, I_OUT=0.5A, L=47μH, T_A=25°C, unless otherwise noted.

Buck-Boost

Buck PWM Dimming

V

= 25V, 3LED, F = 200Hz/50%

DIM

IN

PWM Dimming

Analog Dimming

V

= 25V, 3LED, F

= 200Hz/50%

V

= 25V, 3LED, V

= 0.9A

IN

DIM

IN

DIM

V

IN

V

IN

20V/div.

50V/div.

20V/div.

V

SW

V

SW

50V/div.

20V/div.

50V/div.

V

DIM

V

DIM

5V/div.

2V/div.

5V/div.

I

L

1A/div.

Buck-Boost

Power Ramp Up

Buck-Boost

Enable Power Up

Buck-Boost

Enable Power Down

V

= 8V, 3LED

V

=40V, 3LED

V

= 40V, 3LED

IN

V

IN

50V/div.

5V/div.

50V/div.

SW

50V/div.

V

SW

10V/div.

50V/div.

V

EN

5V/div.

V

OUT

10V/div.

I

L

I

L

1A/div.

0.5A/div.

Buck-Boost

Open LED Protection

Buck-Boost

Short LED Protection

Short LED to VSS

V

= 25V, 3LED, I

LED

= 1A

V

= 16V, 3LED

V

= 25V, 3LED

IN

V

IN

V

IN

10V/div.

20V/div.

V

SW

20V/div.

50V/div.

V

OVP

1V/div.

V

OUT

10V/div.

I

L

1A/div.

I

L

1A/div.

MP24830 Rev. 1.02

4/29/2015

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7

MP24830 — 4.5V–90V, PROGRAMABLE FREQUENCY WHITE LED DRIVER

FUNCTIONAL BLOCK DIAGRAM

CS

DR

DIM

DIMO

COMP

Figure 1: Functional Block Diagram

MP24830 Rev. 1.02

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8

MP24830 — 4.5V–90V, PROGRAMABLE FREQUENCY WHITE LED DRIVER

OPERATION

The MP24830 is a current-mode regulator. The

error amplifier (EA) output voltage is

proportional to the peak inductor current.

LED Short Protection

If the FB voltage exceeds 600mV, the latches

off immediately and DIMO goes low. If the FB

voltage exceeds 300mV for 450µs, the IC

latches off and DIMO is pulled low. The EN

needs to reset to restart the IC.

At the beginning of a cycle, M1 is off. The EA

output voltage exceeds the current sense

amplifier output, and the current comparator’s

output is low. The rising edge of the CLK signal

(its frequency equals the switching frequency)

triggers the RS flip-flop. The driver turns on the

external MOSFET, thus connecting the SW pin

and inductor to the input supply.

Dimming Control

The MP24830 allows both DC and PWM

dimming on the DIM pin. For analog dimming, a

voltage range from 0.6V to 1.95V linearly sets

the LED current from 0% to 100% of the

maximum LED current. DIM voltages exceeding

2V results in the maximum LED current. For

PWM dimming, use a square signal with an

amplitude (V_DIM– V_INGND) that exceeds 1.95V.

For good dimming linearity, select a PWM

frequency in range of 100Hz to 2kHz. For a

higher dimming frequency or dimming ratio, use

the DIMO pin to control an external dimming

MOSFET. For combined analog and PWM

dimming, apply a PWM signal with amplitude of

0.6V to 1.95V on the DIM pin.

The current-sense amplifier (CSA) senses the

increasing inductor current. The PWM

comparator compares the sum of the ramp

generator and the CSA output against the

output of the error amplifier. When the sum of

the CSA output and the ramp generator signal

exceeds the EA output voltage, the RS flip-flop

resets and driver turns off the external

MOSFET. The external Schottky rectifier diode

(D1) conducts the inductor current.

If the sum of the CSA output and the ramp

compensation signal does not exceed the EA

output for a whole cycle, then the falling edge of

the CLK resets the flip-flop.

Output Short-Circuit Protection

The MP24830 integrates output short-circuit

protection (SCP) to foldback the operating

frequency and decrease power consumption

when the output is shorted to VSS. Such shorts

cause the voltage on the OVP pin to drop below

0.4V, and the FB pin senses no voltage (<0.1V)

as no current goes through the WLED.

The output of the EA integrates the voltage

difference between the feedback and the 0.2V

reference: A value of 0.2V-V_FBincreases the EA

output voltage. Since the EA output voltage is

proportional to the peak inductor current,

increasing its voltage also increases the current

delivered to the output.

In buck-boost applications, when there is a

possibility that LED+ short-circuits to VSS, add

a diode from VSS to INGND to protect the IC,

as shown in below in Figure 2.

LED Open Protection

If the LED is open, there is no voltage on the

FB pin. The duty cycle increases until OVP-

VSS reaches the shutdown threshold set by the

external resistor divider. The top switch remains

off until the voltage OVP-VSS drops below 1.2V.

VIN

VDD

EN

OVP

BST

CS

MP24830 _DR

SW

ON

OFF

DIM

INGND

FB

DC or PWM Input

DIMO

VSS COMP RSET

Step-up/down White LED Driver Applicatoin

Figure 2: Buck-Boost Application with Possible

LED+ Short to VSS

MP24830 Rev. 1.02

4/29/2015

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9

MP24830 — 4.5V–90V, PROGRAMABLE FREQUENCY WHITE LED DRIVER

APPLICATION INFORMATION

The MP24830 can be used in buck mode and

buck-boost mode applications.

Where the V_CLis the current limit, V_CL=50mV,

and I_{L_PK_Max}is the maximum peak current in the

inductor.

Setting the LED Current

Calculate R_CSusing the minimum input voltage,

the maximum output voltage and the maximum

output current.

An external resistor R_FBsets the maximum LED

current as per the equation:

0.2V

R_FB

=

I_LED

Setting the Over-Voltage Protection

The MP24380 detects output over-voltage via

the OVP pin. The OVP pin monitors the output

voltage through a voltage divider (R_OVP1and

Setting the Switching Frequency

The switching frequency is set by an external

resistor, R_SET, connected from the RSET pin to

VSS The relationship between the switching

frequency and the programming resister is as

per the following table and shown in Figure 3.

R_OVP2): When the OVP voltage exceeds 1.24V,

the IC triggers OVP.

Select the resistor value ratio using the

following equation:

Table 1 R_SETand f_SWRelationship

V_{OUT _OVP}

R_OVP1

R_OVP2

f_SW(kHz)

R_SET(kΩ)

=

−1

V

th_OVP

100

125

210

400

600

800

1000

350

200

165

100

50.4

30.3

19.9

13.2

Open

The OVP trip-point is set between 0.4V and

1.24V.

Setting the Compensation

The MP24830 implements current-mode control

to regulate the LED current feedback through

the compensation network on the COMP pin.

For most applications, use an RCC

compensation network to ensure current

accuracy and the system stability, as shown in

Figure 4.

Switching Frequency vs.

RSET

1200

1000

Its DC gain is:

800

600

400

200

0

gm×R_FB

DCGain_EA =

C_z+ C_p

Where gm is error amplifier’s transconductance

of 80µA/V.

The zero of the compensation network is:

1

0

50

100

150 200

250

f_{z_EA}

=

2π×R_COMP×C_z

The pole of the compensation network is:

Figure 3: Switching Frequency vs. R_SET

The MP24380 implements current mode control

by sensing the inductor current through a

current sensing resistor R_CS, as calculated by:

0.9× V_CL

1

f_{p_EA}

=

C_z×C_p

C_z+ C_p

2π×R_COMP

×

R_CS

=

I_{L _PK _Max}

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10

MP24830 — 4.5V–90V, PROGRAMABLE FREQUENCY WHITE LED DRIVER

V_OUT

I_OUT* V_OUT

+

R_FB+ R_LEDV_OUT+ V

.

IN

f_{P _PS}

=

2πV_OUT×C_OUT

The right-half plane (RHP) zero of the buck-

boost power stage is:

FB

2

0.2V

V

IN

f_{Z _RHP}

=

R_comp

2π×L ×I_OUT×(V_OUT+ V )

R_FB

IN

C_p

Step 1: Select R_COMP

C_z

Choose a crossing frequency, f_C, below

1/3×f_{Z_RHP}to derive the compensation network

as follow (assume C_Z>>C_p):

VSS

Figure 4: RCC Compensation Network on COMP

(1)Compensation network for Buck-boost

application

f_c

R_COMP

=

gm×R_FB×DCGain_PS * f_{P_PS}

The DC modulator gain of the buck-boost

power stage (from the output current to the

control voltage on COMP pin) is:

That is:

2πf_c×C_OUT× 20×R_CS×(R_FB+ R_LED)(V_OUT+ V )

IN

R_COMP

=

gm×R_FB× V

IN

V_OUT× V

IN

Use the maximum input voltage and minimum

V_OUT+ V

IN

DCGain_PS =

output voltage to calculate R_COMP

.

V_OUT

I_OUT* V

20×R_CS×(

+

^OUT)×(R_FB+ R_LED

)

R_FB+ R_LEDV_OUT+ V

IN

Step 2: Select C_Z

Where R_CSis the switch current sensing resistor

on CS pin, R_LEDis the equivalent dynamic

resistance of the LED load, as shown in Figure

5.

Set the zero of the compensation network to

cancel the minimum pole of the power stage to

get:

1

C_z=

2π× f_{P_PS}×R_COMP

Choose C_Zwith the maximum input voltage and

maximum output voltage.

Step 3: Select C_P

Set the pole of the compensation network to

cancel the minimum RHP zero to get:

ΔV_LED

ΔI_LED

R_LED

=

1

C_p≈

2π× f_{z_RHP}×R_COMP

ΔV_LED

Choose C_Pwith the minimum input voltage and

maximum output voltage.

Figure 5: LED Dynamic Resistance Equivalent

The dominant low-frequency pole of the buck-

boost power stage is:

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MP24830 — 4.5V–90V, PROGRAMABLE FREQUENCY WHITE LED DRIVER

(2)Compensation network for Buck

Selecting the Inductor

application

Select the inductor based on the input voltage,

the output voltage, and the LED current. Select

the inductor to make the circuit operate in

continuous current mode (CCM). Select the

inductor current rating to ensure that the

inductor does not saturate and with

consideration to power consumption based on

the DC resistance.

The DC modulator gain of the buck power stage

(from the output current to the control voltage)

is:

1

DCGain_Buck =

20×R_CS

The dominant, low frequency pole of the buck

power stage is:

(1) Selecting the Inductor for Buck-Boost

Applications

1

f_{P _Buck}

=

For buck-boost applications, select the inductor

based on the following equation:

2π × (R_FB+ R_LED+ R_ESR)× C_OUT

The zero produced by the ESR of the output

capacitor is:

V × V_OUT

IN

L =

f_SW×(V + V_OUT)× ΔI_L

IN

1

f_{Z_ESR}

=

2π×C_OUT*R_ESR

Where ΔI_Lis the peak-to-peak inductor current

ripple. Design ΔI_Lto be between 30% and 60%

of the average current of the inductor, which is:

Where R_ESRis the ESR of the output capacitor.

Step 1: Select R_COMP

V_OUT

I_{L _ AVG}= I_LED* (1+

)

Choose a crossing frequency, f_C, below 1/5×f_C

to derive the compensation network as follows

(assume C_Z>>C_P):

V

IN

Select the inductor with a DC current rating that

ensurew that the inductor does not saturated at

the peak current of:

f_c

R_COMP

_

=

Buck

gm×R_FB×DCGain_Buck * f_{p_Buck}

I_{L_PK}= I_{L_ AVG}+ 0.5ΔI_L

That is:

2πf_c×C_OUT× 20×R_CS×(R_FB+ R_LED+ R_ESR

gm×R_FB

)

(2) Selecting the Inductor for Buck Applications

R_{COMP _Buck}

=

For buck applications, derive the inductance

value from the following equation.

Step 2: Select C_Z

V_OUT× (V_IN− V_OUT

V_IN× ΔI_L× f_SW

)

Set the zero of the compensation network to

cancel the minimum pole of the Buck power

stage to get:

L =

Where ΔI_Lis the peak-to-peak inductor ripple

current.

1

C_{z _Buck}

=

2π × f_{P _Buck}×R_{COMP _Buck}

Choose the inductor ripple current to around

30% to 60% of the maximum load current. The

maximum inductor peak current is calculated as:

Step 3: Select C_P

Set the pole of the compensation network to

cancel the ESR zero. If the ESR zero is too

high, set this pole at around 3 to 5 times f_C:

ΔI_L

I_L(MAX)= I_LOAD

+

2

Selecting the Input Capacitor

1

C_p≈ max(

,

)

2π× f_{z_ESR}×R_{COMP_Buck}2π×5f_c×R_{COMP_Buck}

The input capacitor reduces the surge current

drawn from the input supply and the switching

noise from the device. For best results, use

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12

MP24830 — 4.5V–90V, PROGRAMABLE FREQUENCY WHITE LED DRIVER

ceramic capacitors with X7R dielectrics with low

PC Board Layout

ESR and small temperature coefficients.

Place the high-current paths (VSS, VDD and

SW) very close to the device with short, direct,

and wide traces. Place the input capacitor as

close as possible to the VDD and VSS pins.

Place the external feedback resistors next to

the FB pin. Keep the switch node traces short

and away from the feedback network.

Select a large-enough capacitor to limit input

the voltage ripple, ΔV_IN, to less than 5% to 10%

of the DC value.

I_{L _ AVG}× V_OUT

C_IN

>

f_SW× ΔV ×(V + V_OUT

)

IN

Pay special attention is required to the

switching frequency loop layout, which should

be as small as possible.

Selecting the Output Capacitor

The output capacitor limits the output voltage

ripple, ΔV_OUT(normally less than 1% to 5% of

the DC value), and ensures feedback loop

stability. Use an output capacitor with

impedance at the switching frequency. Use

ceramic capacitors with low ESR characteristics.

For buck applications, the switching frequency

loop is composed of the input capacitor, the

power MOSFET and the Schottky diode. Place

the Schottky diode close to the power MOSFET

and the input capacitor.

I_LED× V_OUT

C_OUT

>

For buck-boost or boost applications, the

switching frequency loop is composed of the

input capacitor, the power MOSFET, the

Schottky diode and the output capacitor. Make

this component loop as small as possible. For

most applications, place the output capacitor

close to the input capacitor and the power

MOSFET.

f_SW× ΔV_OUT×(V + V_OUT

)

IN

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13

MP24830 — 4.5V–90V, PROGRAMABLE FREQUENCY WHITE LED DRIVER

TYPICAL APPLICATION CIRCUIT

Figure 6: Step-up/down White LED Driver Application

Figure 7: Step-down Constant Voltage Converter Application

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14

MP24830 — 4.5V–90V, PROGRAMABLE FREQUENCY WHITE LED DRIVER

PACKAGE INFORMATION

SOIC-14

0.338(8.55)

0.344(8.75)

0.024(0.61)

0.050(1.27)

8

14

0.063

(1.60)

0.150

(3.80)

0.157

(4.00)

0.228

(5.80)

0.244

(6.20)

0.213

(5.40)

PIN 1 ID

7

1

TOP VIEW

RECOMMENDED LAND PATTERN

0.053(1.35)

0.069(1.75)

0.0075(0.19)

0.0098(0.25)

SEATING PLANE

0.050(1.27)

BSC

0.013(0.33)

0.020(0.51)

0.004(0.10)

0.010(0.25)

SEE DETAIL "A"

SIDE VIEW

FRONT VIEW

NOTE:

0.010(0.25)

0.020(0.50)

x 45^o

1) CONTROL DIMENSION IS IN INCHES. DIMENSION IN

BRACKET IS IN MILLIMETERS.

GAUGE PLANE

0.010(0.25) BSC

2) PACKAGE LENGTH DOES NOT INCLUDE MOLD FLASH,

PROTRUSIONS OR GATE BURRS.

3) PACKAGE WIDTH DOES NOT INCLUDE INTERLEAD FLASH

OR PROTRUSIONS.

4) LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING)

SHALL BE 0.004" INCHES MAX.

5) DRAWING CONFORMS TO JEDEC MS-012, VARIATION AB.

6) DRAWING IS NOT TO SCALE.

0.016(0.41)

0.050(1.27)

0^o-8^o

DETAIL "A"

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15

MP24830 — 4.5V–90V, PROGRAMABLE FREQUENCY WHITE LED DRIVER

QFN-14

1.60

1.80

2.90

3.10

0.30

0.50

PIN 1 ID

SEE DETAIL A

PIN 1 ID

MARKING

1

14

0.18

0.30

3.20

3.40

3.90

4.10

PIN 1 ID

INDEX AREA

0.50

BSC

7

8

TOP VIEW

BOTTOM VIEW

PIN 1 ID OPTION A

0.30x45” TYP.

PIN 1 ID OPTION B

R0.20 TYP.

0.80

1.00

0.20 REF

0.00

0.05

SIDE VIEW

DETAIL A

2.90

1.70

NOTE:

0.70

1) ALL DIMENSIONS ARE IN MILLIMETERS.

2) EXPOSED PADDLE SIZE DOES NOT INCLUDE MOLD FLASH.

3) LEAD COPLANARITY SHALL BE 0.10 MILLIMETER MAX.

4) JEDEC REFERENCE IS MO-229, VARIATION VGED-4.

5) DRAWING IS NOT TO SCALE.

0.25

3.30

0.50

RECOMMENDED LAND PATTERN

NOTICE: The information in this document is subject to change without notice. Users should warrant and guarantee that third

party Intellectual Property rights are not infringed upon when integrating MPS products into any application. MPS will not

assume any legal responsibility for any said applications.

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16

型号:	MP24830HS-LF-Z
是否无铅：	不含铅
是否Rohs认证：	符合
生命周期：	Active
Reach Compliance Code：	compliant
ECCN代码：	EAR99
HTS代码：	8542.39.00.01
Factory Lead Time：	8 weeks
风险等级：	1.73
Base Number Matches：	1

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